Preheat the oven to 425°F (220°C). Toss the peeled, diced sweet potatoes with 2 tablespoons olive oil, 1½ teaspoons paprika, 1 teaspoon garlic powder, and salt and pepper to taste; spread in a single layer on a sheet pan.
Roast the sweet potatoes until tender and golden, about 30 minutes, flipping every 10 minutes.
When the potatoes are nearly done, add the frozen corn and drained black beans to the pan and toss to warm through; set aside.
Heat 1 tablespoon olive oil in a large nonstick skillet over medium-high heat. Add the diced onion (if using) and sauté 3–5 minutes until golden.
Push the onions to the edge of the skillet and add the ground beef to the center. Sear, crumble, and cook until browned and most liquid has evaporated.
Stir in 1/4 cup chicken broth or water, the 1-ounce taco seasoning packet, 2 tablespoons tomato paste, and 1½ teaspoons minced garlic (if using). Cook 1–2 minutes until fragrant, then remove from heat.
Zest one or two limes to get about 1/4 teaspoon zest and squeeze to collect about 3 tablespoons juice. In a small bowl, whisk the zest and juice with 1/2 cup mayo or Greek yogurt, 1/2 teaspoon chili powder, 1/2 teaspoon paprika, 1/2 teaspoon ground cumin, 1 teaspoon Sriracha, and salt and pepper to taste.
Divide the seasoned beef among 4 bowls. Top each with the roasted sweet potato, corn, and black bean mixture, and diced avocado. Drizzle with the lime-Sriracha sauce and, if desired, a little hot honey.
